为了揭示三轴压缩下砂岩的细观破裂规律，本文以砂岩室内三轴压缩试验为基础，结合非均质晶质模型（Grain-Based model, GBM）和矩张量理论模拟砂岩内部裂纹衍生、声发射事件及破裂强度发展特征，推导出砂岩内微裂纹衍生过程、声发射响应特征规律，从细观尺度上综合分析裂纹以及声发射事件的时空演化过程。研究结果表明：在三轴压缩下砂岩的起裂阶段内，微裂纹在试样内部随机分布，位移场呈水平层状分布。随着载荷增加，微裂纹增多并逐渐贯通成两条宏观裂纹，位移场偏移且非均质性明显；裂纹在孕育期发展缓慢，当达到发展期时，裂纹以极高的非线性速率增长，裂纹发展顺序为晶间拉伸裂纹、晶间剪切裂纹、晶内拉伸裂纹、晶内剪切裂纹；试样内部拉伸裂纹占比高达83.2%，以拉伸破坏为主；试样声发射事件数与裂纹条数呈负指数关系，单次声发射事件产生一条微裂纹次数占比为75.60%，声发射事件数、微裂纹数与破裂强度近似呈正态分布。

This paper aims to investigate the mesoscopic fracture mechanisms of sandstone under triaxial compression. We conducted indoor triaxial compression tests of sandstone and integrated the Grain-Based Model (GBM) and moment tensor theory to simulate the development characteristics of internal cracks, acoustic emission events, and fracture strength in sandstone. Derive the derivation process of microcracks and the characteristics of acoustic emission response in sandstone, and comprehensively analyze the spatiotemporal evolution process of cracks and acoustic emission events at the micro scale. The results indicate that microcracks are randomly distributed in the sandstone sample during the initiation stage of fracture under triaxial compression, and the displacement field shows a horizontal layered distribution. As the load increases, the number of microcracks increases, penetrates gradually into two macroscopic cracks, and shifts the displacement field to a significant heterogeneity. The cracks in the incubation periodshow slow development, andCracks grow at extremely high nonlinear rates. The order of crack development follows a sequence of intergranular tensile cracks, intergranular shear cracks, intragranular tensile cracks, and intragranular shear cracks. The simulation analysis revealed that the majority of internal cracks triaxial compression (83.2%) are tensile cracks resulting from tensile failure. The number of acoustic emission events in the samples has a negative exponential correlation with the number of cracks, and a single acoustic emission event generates 75.60% of microcracks. Finally, the analysis of acoustic emission events, the number of microcracks, and the fracture strength indicates that the three factors approximately follow a normal distribution.

国家自然科学基金(61731016)